New phase-modulation control technology for multiple output power supplies delivers ease of design and high performance using fewer components

Recent advancements in power IC technology have yielded design solutions which can significantly reduce the size, cost and complexity of multiple output power supplies while, at the same time, greatly improve the maximum operating frequency limit, efficiency and overall robustness of these power supplies. The author describes the compact LX1571 controller IC which not only reduces cost and board space requirements of these power supplies, but, by replacing the core used in mag-amp designs with a low, on-resistance MOSFET, permits the use of switching frequencies above 100 kHz. In addition, because the MOSFET turns on before the AC input, the use of this IC provides 100% energy transfer. The complexity of these designs can be further reduced through the use of a pre-assembled and tested evaluation board, which houses the LX1571 power IC and demonstrates its long list of protection features.